1. Field of the Invention
This invention relates to a single-stage and a multiple-stage fluidic rectifier wherein each stage of the rectifier has a trunk channel and a reversing channel. In a reverse flow direction, a first vena contracta is formed when fluid enters the trunk channel through a sharp edge orifice. At least one second vena contracta is formed within at least one downstream trunk channel by flow through a reversing channel being discharged into the downstream trunk channel such that the discharged flow from the reversing channel impinges upon and contracts fluid flow through each trunk channel.
2. Description of Prior Art
Conventional apparatuses that act as fluid diodes are known to have no moving parts. However, such conventional apparatuses with no moving parts do not operate with trunk channels and reversing channels to form vena contractas at an entry of fluid into the apparatus and throughout each stage of the fluidic diode.
Tesla, U.S. Pat. No. 1,329,559 discloses a valvular conduit which allegedly offers virtually no resistance to the passage of fluid in one direction, other than surface friction, but is an almost impossible barrier to flow in the opposite direction. At an initial glance, FIG. 1 of the Tesla patent appears to teach the invention of this patent application. However, upon further study it will become apparent that the invention taught by this specification has dominating features and significant improvements which would not be obvious in view of the teachings of the Tesla patent, particularly when taken in view of the technical opinions of recognized authorities in fluid mechanics. The invention described in this specification and the claims produces unexpected results which significantly increase the overall head loss ratio of a single-stage or multiple-stage fluidic rectifier.
At page 1, lines 100-106, the Tesla patent teaches an approximate path which is nearly straight in the easy or forward direction of flow through the apparatus. FIG. 7 of the drawings associated with this specification show a modified drawing of FIG. 1 of the Tesla patent, modified by the addition of a straight line drawn through the central channels showing that core flow can follow an exact straight line in the easy or forward direction according to the teachings of the Tesla patent.
The apparatus of this invention operates directly contrary to the teachings of the Tesla patent. As the trunk channels of this invention are straightened, the overall head loss performance significantly decreases as a function of the straightening of the trunk channels. According to this invention, experiments have shown that the best overall head loss performance occurs when fluid flow is directed through trunk channels which deflect the flow at 45.degree. angles with respect to each other. At page 2, lines 40-47, the Tesla patent teaches the flow in the hard or reverse direction experiencing only two small deviations from about 10.degree. to 20.degree.. At page 2, lines 57-62, the Tesla patent specifically teaches that in order to keep the head loss ratio as large as possible, sharp bends should be avoided, for these will add to both resistances and reduce the efficiency, and further teaches that whenever practicable, a piece should be straight.
FIGS. 8 and 9 of the drawings associated with this specification show a single-stage and a two-stage fluidic rectifier 20 wherein the trunk deflects at an angle of 15.degree. with respect to a rectilinear axis parallel to rectilinear flow entering the body, and thus deflects at an angle of 30.degree. with respect to adjacent channels. In an experiment conducted with such two-stage fluidic rectifier 20 of this invention, with the 30.degree. deflection from one trunk channel to the next, the overall head loss ratio was 1.97. With the single-stage fluidic rectifier 20 having the 30.degree. deflection from one trunk channel to the next, the overall head loss ratio was 1.42. As will be shown later in this specification, with the 45.degree. deflection, the two-stage fluidic rectifier 20 of this invention produced an overall head loss ratio of 7.3, and the single-stage fluidic rectifier 20 having the 45.degree. deflection produced an overall head loss ratio of 4.7-4.8, both of which are significantly improved when compared to the 30.degree. deflection.
The Tesla patent suggests straightening the core channel, which may be viewed as the equivalent of the trunk channel of this invention, in order to increase the overall head loss ratio of the fluidic rectifier. Directly contrary to the teachings of the Tesla patent, experiments have shown that increasing such angle of deflection to approximately 45.degree. optimizes the overall head loss ratio of this invention. It is important to note that this invention includes other differences in channel design and guide vane placement, as well as specific ventilation, specific entry elements or designs, and specific discharge configurations, with respect to flow in the hard or reverse direction, to achieve such drastically different and better overall head loss ratios.
The Tesla patent teaches relatively long and thin guide vanes. Such long and thin guide vanes tend to shave off or divert a portion of the core flow and route it into the reversing channel. As the flow passes through the reversing channel taught by the Tesla patent, the flow will lose appreciable energy and will simply discharge into and combine with the dominating, high-speed core flow. The flow discharged from the reversing channel taught by the Tesla patent will not span the core flow and will not enter the next reversing channel, as the dashed arrows of FIG. 1 of the Tesla patent show, since there will be extremely large energy differences between the core flow and the flow through the reversing channel.
At page 2, lines 6-10, the Tesla patent teaches that the partitions or guide vanes serve to direct the stream upon the reversing channels and to intensify the actions causing violent surges and eddies which interfere very materially with the flow through the conduit. According to the invention described in this specification and in the claims, eddies and other energy sinks are avoided since the apparatus of this invention uses the available energy to contract the flow area and obtain a head loss.
The Tesla patent teaches pipe nipples for the entries on both ends of the device. Quite contrary to such teachings of the Tesla patent, the invention defined by this specification and claims requires a sharp edge orifice for creating a vena contracta upon entry of the fluid into the trunk channel of the body. Forming such first vena contracta is a crucial aspect of this invention and significantly enhances the overall head loss ratio, as compared to the apparatus taught by the Tesla patent.
In view of the teachings of the Tesla patent and many comments regarding such apparatus by well-known authorities in fluid mechanics, it is apparent that there is a need for a fast-acting, responsive fluidic rectifier which has no moving parts and can be mass produced at reduced costs, particularly for use with a pulse combustor.